Hello, Poor concentration at your age may be related to multiple factors like stress, family circumstances, difficulty with people around you, poor planning, depression, anxiety, poor eyesight, hearing  vision and many many more possible factors. As you can see that it is difficult to discern the exact problems from a singular complaint. However a comprehensive assessment can help you understand the reason behind your symptom. Hence please seek a consultation with a psychiatrist near you for comprehensive assessment... Hope this helps you.. Best wishes for your health and future...